TORONTO - The widow of Jack Layton implored New Democrats on Friday to continue to grow his work and reap the harvest as the NDP paid tribute to the man who led it to the gates of Canada's electoral promised land.

With tens of thousands of card-carrying party members poised to choose Layton's successor on Saturday, Olivia Chow told the leadership convention "we have come through a winter of challenge and change together and now it is spring."

"It is springtime for the New Democrats!" said Chow, to applause and cheers.

Chow's speech followed a sometimes moving, sometimes funny 60-minute tribute ceremony at the Metro Toronto Convention Centre, played before a backdrop of scrawled sidewalk chalk messages on video screens taken from Layton's August 2011 memorial.

Throughout, a near-capacity crowd of several thousand clapping delegates frequently rose to their feet in applause, most of them clad in white T-shirts bearing the slogan, "I am the Layton legacy."

The rousing message of the night: keep looking forward and avoid the trap of stalling in misty memories of Layton, who died of cancer at age 61 last August — less than four months after a landmark federal election gave the NDP 103 seats and official Opposition status for the first time ever.

In the same week that a byelection victory allowed the NDP to reclaim Layton's vacant downtown Toronto seat, the party's leadership convention used his legacy to foretell a bright NDP future.

Nonetheless, Layton's spirit has haunted the seven-month leadership race, his name invoked endlessly by the large field of would-be successors.

Those invocations carried right on to the convention floor earlier Friday afternoon as the remaining seven candidates made their last pitches to voters. Tens of thousands of voting NDP party members will elect a new leader Saturday.

Nathan Cullen, the first of the seven to address the convention floor Friday, opened his speech by stating the convention subtext — that vying for the party leadership was not in the playbook last May 2.

"This wasn't my plan," Cullen began.

Thomas Mulcair, the former Quebec Liberal cabinet minister and acknowledged front-runner, said the convention is "about building on what Jack has already accomplished and moving forward from there."

Niki Ashton, the youngest leadership hopeful, peppered her speech with Layton references by telling the receptive crowd that he prepared the party for achieving power in the next federal election.

"Friends, we may have lost Jack, but we must not lose our way," implored yet another leadership hopeful, Paul Dewar.

The evening tribute was more upbeat, and less cautionary.

For the duration, a chalk artist working at the back of the stage scratched out a picture-perfect portrait of the late NDP leader, his work projected around the cavernous hall on LED screens as a nod to the outpouring of public sidewalk chalk tributes that Canadians scrawled last August during days of mourning.

Two former prime ministers — needless to say, neither of them New Democrats — spoke to the convention delegates by video.

Jean Chretien called Layton a "professional politician," then hastened to add that his life of public service was a tribute to that professionalism. Brian Mulroney called him "an entertaining, charming, interesting guy" and said the NDP's success in Quebec was "not an accident."

It was announced that a park in Hudson, Que., Layton's home town, will be named after him, and the party confirmed reports that its downtown Ottawa headquarters will be formally renamed the Jack Layton Building.

Environmentalist David Suzuki and former Newfoundland premier Danny Williams spoke by video; Shawn Atleo, national chief of the Assembly of First Nations, and Bill Blaikie — the venerable former Manitoba MP who Layton defeated for the party leadership in 2003 — were among those who gave live tributes.

"Teamwork was something Jack was very good at," Blaikie said, a pointed message heading into a weekend leadership decision with party fissures clearly showing.

Atleo credited the "energy and optimism of this night" and told the crowd that "Jack's indomitable spirit has been magnified and multiplied." And he took a gentle poke at the bitter partisanship that is the temper of the times, noting the native tradition of storytelling, listening and an underlying first principle for interaction: "to be open and friendly, and especially to show love."

The hour-long tribute didn't skip the comedic, with video clips from Layton's many self-mocking TV appearances on shows such as "This Hour has 22 Minutes," "The Rick Mercer Report" and "Infoman." Jean-Rene Dufort, the frontman for the French-language "Infoman," issued a challenge to the next party leader to follow Layton on to the popular show and flip burgers.

There was also emotion. Layton's children Mike and Sarah were part of a moving family video montage, speaking frankly of his last days. "There was hope into the last hours," a teary-eyed Sarah told the camera.

Layton's own voice speaking of a better world for his granddaughter Beatrice had the convention hall rapt and silent.

But it was Olivia Chow who got the crowd back on its feet with her claim that last spring's "Orange Crush" is staying and growing.